> We are planning to add new moodle server for backup ...
Do you mean backup in the sense of taking copies so that you can restore the service after a mishap or do you mean failover, a standby computer which would take over once the original computer breaks down?
> and load balancing.
Perhaps you meant the latter. In addition to failover, you require the second machine to share the load during normal operation.
> We bought new high end server for load balancing, fault tolerence.
OK. You are going for better performance _and_ high availability.
> Could you please guide me how to configure and implement it?
This is a sophisticated subject which goes far beyond the scope of Moodle itself. That is also the reason, why there is no recommended solution for this in moodle.org. But there have been many user discussions and suggestions in this forum. Go through them. Make use of the search facilities as documented in the introduction to this forum 'Hardware and Performance'.